Sheet-metal working hammer having a divided head portion



Sejit. 29, 1959 J. w. STEWART 2,906,150

SHEET-METAL WORKING HAMMER HAVING A DIVIDED HEAD PORTION Filed April 1, 1958 2 Sheets-Sheet 1 iNVENTOR. JAMes W$rewmrr ATTORNEYS P 1959 J. w. STEWART 0 0 SHEET-METAL WORKING HAMMER HAVING A DIVIDED HEAD PORTION Filed April 1, 1958 2 Sheets-Sheet 2 FIG. 5

a INVENTOR. JAM as W. STEWART A# TorzNEYs United States Patent SHEET-METAL WORKING HAMMER HAVING A DIVIDED HEAD PORTION James W. Stewart, Boise, Idaho Application April 1, 1958, Serial No. 725,578

12 Claims. (Cl. 8115) This invention relates generally to hammers and like tools, and more particularly has reference to a hammer head which is novelly formed in such a manner as to be usable to particular advantage in straightening dents in various types of metals. Accordingly, while it is presently contemplated that the readiest application of the hammer would be in automobile body repair shops, as will presently appear the invention is not limited to this particular use, since the hammer is adapted for employment to advantage in any situation requiring the straightening of metal.

Ordinarily, when a hammer head is brought forcibly againsta metallic surface that has been dented, for the purpose of straightening out the dent, the effect of the blow is to push metal away from the point of impact, in all directions radially outwardly from said point. Obviously, this causes a thinning of the metal at the impact point. This stretching of the metal is, of course, extremely undesirable, and tends to weaken the metal as well as prevent the rapidand fully efficient straightening of the dent.

According to the present invention, the hammer head has a pluralityof segmentally shaped sections, which cooperate to normally provide a slightly convex, workstriking face on the hammer head. Resilient, yielding means is associated with said segments, and th segment are somounted in the body portion of the hammer head, that when the head is brought forcibly against the work,

the segments are drawn toward each other in a direction radially inwardly of the center point of the convex face of the hammer head, producing a grasping action by the hammer head that results in an actual shrinking of the surface that is struck, rather than the above mentioned opposite condition of a stretching, produced by an ordinary hammer.

An important object of the present invention, accordingly, is to provide a generally improved hammer head for use particularly in situations such as those described above, which hammer head will tend to draw metal toward the point of impact, rather than away therefrom.

Another object is to provide a hammer head of the character described which will produce the above mentioned novel, desirable action even if the head is not struck squarely against the work, that is, even if the marginal portion of thesegmental head strikes the work rather than the centerpoint thereof.

A further object is to provide a hammer head of the type statedwhich will have associated therewith means for adjusting the tension of a spring that yieldably opposes movement of the several segments radially inwardly toward each other. In this way, it is proposed to permit the pressure against the segments to be adjusted, so that when heavier pressure is exerted thereon the device operates with maximum efficiency on heavier metal,

while conversely, when the pressure is lightened against the faces of the several segments, the device is adapted for use to particular advantage onsofter metals.

A further object of importance is to provide a ham-- I mer of the character described which will be designed for ready replacement of any segment or segments, so that segments having various different types of scorings in their work-engaging faces can be interchangeably employed, and so that, further, segments that have been damaged or have become worn by long use can be replaced without requiring replacement of the entire hammer.

Another object of the invention is to provide a hammer of the type described which will be usable either as a component of automatically operating hammering tools, such as an air hammer, or alternatively, can be used as a component of a hand tool, such as an ordinary hammerlike article having a handle and a head secured to one end of the handle.

Another object is to provide a device of the character stated that will be usable to maximum advantage in connection with automobile body repair work, while still being adapted for employment in a large number of other situations.

Another object of importance is to provide a hammer of the character described that will be capable of manufacture at a comparatively low cost, considering the benefit to be obtained from the use thereof.

Other objects will appear from the following description, the claims appended thereto, and from the annexed drawings in which like reference characters designate like parts throughout the several views and wherein:

Figure l is a perspective view of a hammer according to the present invention, the work-engaging face thereof projecting upwardly;

Figure 2 is a plan view of the hammer as shown in Figure 1, a portion of the handle being broken away;

Figure 3 is a sectional view, on an enlarged scale, taken substantially on line 3-3 of Figure 1;

Figure 4 is a transverse sectional view substantially on line 44 of Figure 3;

Figure 5 is a sectional view on line 55 of Figure 2;

Figure 6 is a fragmentary, exploded perspective view of the hammer head; and

Figure 7 is a view on approximately the same plane as Figure 5, showing the hammer as it appears when in use.

Referring to the drawing in detail, designated at 10 is a conventional hammer handle having a reduced extension 12 adapted to receive a wedge 14 for tightly engaging the extension in a'transverse opening 16, formed in the intermediate portion of an elongated body part 18 of the hammer head 19 constituting the present invention.

At this point, it will be understood that a hammer of the hand-tool type has been illustrated purely by way of example in the several figures of the drawing. However, the invention resides in the head 19, and not in the handle 10. It will be therefore understood that the body part 18 of the invention can be shaped in any desired way, according to the type of tool in which it is to be used. Therefore, if the device is to be incorporated in a machine tool, such as an air hammer, the body part would be so shaped as to be mountable within a cooperating, adjacent component of the air hammer. This is considered sufficiently obvious not to require special illustration herein. The invention, in other words, resides in the hammer head 19, and regardless of the manner whereby said hammer head is brought forcibly against the work surface, the principles of operation remain unchanged.

In any event, the illustrated example shows the body part 18 tapering in opposite directions from the transverse opening 16, and at one end, the body part 18 has an elongated, tapering extension 20. At its other end, body part 18 is formed with an approximately hemispherical end portion 22, the planiform, circular surface 23 of which faces away from the body part 18,

Centrally formed in the end portion 22 is a comparatively large diameter recess 24, extending axially of the hammer head and communicating at its inner end with an elongated, threaded, small diameter bore 26.

An impact assembly generally designated 28 comprises a plurality of segmentally shaped members 30. Each of these extends through 90 degrees of a circle at its outer periphery. Therefore, the segments are quadrantal, with each segment being substantially in the shape of a oneeighth portion of a sphere.

The several segments are fitted together in the manner shown in Figure l, to produce an impact head which is of generally hemispherical configuration, with the convex surface of said head being disposed in position centrally seated upon the flat outer end surface 23 of the enlargement or end portion 22.

Referring now to Figure 6, wherein the individual construction of the segments is shown to perhaps its best advantage, it will be seen that each segment 30, at its base, has a tongue 32 terminating at its outer end in a laterally outwardly extending projection 33 on the outer end of which is formed a spherical enlargement 34. Referring further to Figure 6, and also to Figure 5, angularly spaced about the marginal portion of the end portion 22 are circular, deep recesses 36 proportioned to snugly receive the spherical enlargements 34. Recesses 36 communicate with radial slots 38 which provide communication between the recesses 36 and the center recess 24, and which are adapted to receive the extensions 33.

Thus, it may appropriately be considered that each segment 30 at its inner end, that is, the end seating in the portion 22 of the hammer head, has a radially outwardly extending arm defined by tongue 32 and extension 33 terminating in a ball element 34 at its outer end, said element rocking on portion 22 due to rotatable engagement of the ball element in the inner, hemispherical end of its associated recess 36. The segments rock between the opposite positions shown in Figures and 7 respectively, and are normally disposed in the Figure 5 positions.

Designated at 40 is a screw provided with a large, flat head disposed within center recess 24, said screw having a threaded shank 42 engageable in the threaded bore 26. Bearing at one end against the head of the screw is compression coil spring 44 extending axially within recess 24 and hearing at its other end against the arms of the segments 30 to normally bias the segments to their Figure 5 positions. Thus, each segment rocks on its ball element 34 outwardly of the end portion 22, so that the work-engaging face of the hammer head ordinarily is bulged outwardly as shown in Figures 3 and 5.

A plurality of screws 46, angularly spaced about the portion 22, extend through openings provided in approximately semi-circular, confronting, hold-down plates 48, 50, the plate 50 having upwardly offset ends overlapping the ends of the plate 48. The plates are in engagement with the marginal surface of the portion 22 so as to hold the segments to the portion 22 in the normal position shown in Figures 3 and 5.

Designated at 52 are score marks provided in the workengaging faces of the several segments. Said score marks are in the form of arcuate concentric grooves, defining correspondingly shaped serrations or ribs, the several grooves meeting at opposite ends of the respective segments to provide continuous concentric grooves when the several segments are assembled with each other. This scoring of the work-engaging faces of the segments causes the segments to effectively grip. the metal when a blow is directed against the metal.

At 54 there have been designated radial grooves angularly spaced 90 degrees apart about the head (see Figure 2) and meeting at the center point of the head, said grooves being progressively increased in width in a direction toward said center point of the head. The grooves are defined by reason of the fact that the several segments are rocked upwardly under thepressure of th pr 44,

to the normal position shown in Figure 5. The grooves provide room for the segments to swing from their Figure 5 to their Figure 7 positions during use of the device.

Designated at 56 is a work piece, such as the body of an automobile having in it a dent 58 that is to be straightened.

With the device assembled in the manner previously illustrated and described herein, it is usable to advantage for any of the various purposes described above. The spring is placed under suitable tension, since the screw 4t) can be threaded outwardly or inwardly of the recess, to whatever extent is necessary. The adjustment of the position of the screw is efiected, of course, with the segments removed.

The smaller the distance between the head 40 of the screw and the arms of the several segments, the greater will be the compressional action imparted to the spring, that is, the spring will be placed under greater pressure and will exert a strong pressure against the segments tending to increase their resistance to movement from their Figure 5 to their Figure 7 positions.

As will be observed from Figure 5, under the pressure of the spring the inside corners, that is, the corners of the segments disposed at the center of the head, are slightly raised, that is, forced outwardly of the body part 18 in a direction toward the work. When, then, the hammer is swung against the work as in Figure 7, the first portions of the faces of the segments to strike the work are the inside corners, which are thus caused to be forced to gether, causing a grasping action by the faces of the segments against the work, resulting in an actual shrinking of the surface struck, rather than the adverse condition of a stretching action which occurs with an ordinary hammer. In other words, the work is drawn toward the center point of the hammer surface. The force of the blow places the spring temporarily under compression as shown in Figure 7, and the several, scored faces of the segments move substantially into coplanar relationship for an instant. When the hammer is raised, the spring expands and the several faces move back to the position shown in Figure 5 before the next blow is struck.

In addition to the adjustable setting of the spring tension in the hammer head, the size of the hammer would also be increased or decreased considering the type of the job, the size of the job, and the type of metal being worked. It is contemplated that in extremely heavy jobs the hammer would be increased in size sufficiently to handle the necessary work, and would of course be made correspondingly smaller for smaller jobs.

In addition to different sizes of hammers and the change of settings of the tension on the faces of the hammers, the hammer faces themselves may be varied so as to adapt the same to different types and sizes of jobs. For example, rubber, soft metal, and hard metal hammer faces can be interchangeably employed, depending upon the purpose to be achieved.

Also, the scorings in the hammer faces may be changed in depth, design and direction to achieve different actions necessary in straightening different metals. These, of course, would be refinements of the invention believed sufficiently obvious as not to require special illustration herein.

An advantage of the action of the hammer is found in the fact that even though the blow may not be direct, that is, even though the impact may not be at the exact center of the outwardly bulged work-engaging surface, the tension of the spring on the other hammer faces, those that do not initially strike the work, tends to level out the action and prevent a denting or stretching of the metal. The principle is that the hammer, due to its novel construction, always hits evenly on the surface of the material struck and pulls or grasps the metal, pushing the same in a direction radially, inwardly of the work-engaging face of the device, so as to eliminate denting, stretching, and of the metal.

It is believed apparent that the invention is not necessarily confined to the specific use or uses thereof described above, since it may be utilized for any purpose to which it may be suited. Nor is the invention to be necessarily limited to .the specific construction illustrated and described, since such construction is only intended to be illustrative of the principles, it being considered that the invention comprehends any minor change in construction that may be permitted within the scope of the appended claims.

What is claimed is:

1. In a sheet-metal working hammer, a divided head portion comprising a body having a centerrrecess; a plurality of segmentally shaped impact sections having arms extending'into said recess, said arms being rockably supported uponthe body, the sections rocking on the body toward each other responsive to movement of the sections against a work piece, said sections comprising a generally hemispherical impact head; and resilient, yielding means normally biasing the sections away from each other.

2. In a sheet-metal working hammer, a divided head portion comprising a body having a center recess; a plurality of segmentally shaped impact sections having arms extending into said recess, said arms being rockably supported upon the body, the sections rocking on the body toward each other responsive to movement of the sections against a work piece, said sections comprising a generally hemispherical impact head; and resilient, yielding means normally biasing the sections away from each other, comprising a compression coil spring extending within said recess and bearing at one end against said arms, and a screw mounted in the recess for movement toward and away from the arms, the spring bearing at its other end against the screw.

3. In a sheet-metal working hammer, a divided head portion comprising a body having a center recess and having a series of marginal recesses angularly spaced about and communicating with the center recess; a plurality of segmentally shaped impact sections having arms extending into said center recess, said arms being formed with spherical enlargements rockably engaged in the several marginal recesses, for rocking of'the arms upon the body, the sections rocking with their arms toward each other responsive to movement of the sections forcibly against a work piece, said sections comprising a generally hemispherical impact head; and resilient, yielding means within the center recess normally biasing the sections away from each other.

4. In a sheet-metal working hammer, a divided head portion comprising a body having a center recess and having a series of marginal recesses angularly spaced about and communicating with the center recess; a plurality of segmentally shaped impact sections having arms extending into said center recess, said arms being formed with spherical enlargements rockably engaged in the several marginal recesses, for rocking of the arms upon the body, the sections rocking with their arms toward each other responsive to movement of the sections forcibly against a work piece, said sections comprising a generally hemispherical impact head; and resilient, yielding means within the center recess normally biasing the sections away from each other, each of said sections being of quadrantal shape.

5. In a sheet-metal working hammer, a divided head portion comprising a body having a center recess and having a series of marginal recesses angularly spaced about and communicating with the center recess; a plurality of segmentally shaped impact sections having arms extending into said center recess, said arms being formed with spherical enlargement rockably engaged in the several marginal recesses, for rocking of the arms upon the body, the sections rocking with their arms toward each other responsive to movement of the sections forcibly against a work piece, said sections comprising a generally hemispherical impact head; and resilient, yielding means within the center recess normally biasing the sections away from each other, each of said sections being of quadrantal shape, said sections when rocked away from each other under the pressure of the spring being spaced apart slightly along adjacent surfaces of adjacent sections, the sections having flat, work-engaging faces forming a bulged work-engaging surface on the impact head when the sections are rocked away from each others 6. In a sheet-metal working hammer, a divided head portion comprising a body having a center recess and having a series of marginal recesses angularly spaced about and communicating with the center recess; a plurality of segmentally shaped impact sections having arms extending into said center recess, said arms being formed with spherical enlargements rockably engaged in the several marginal recesses, for rocking of the arms upon the body, the sections rocking with their arms toward each other responsiveto movement of the sections forcibly against a'work piece, said sections comprising a generally hemispherical impact head; and resilient, yielding means within the center recess normally biasing the sections away from each other, each of said sections being of quadrantal shape, the sections when rocked toward each other on striking of a blow against the work moving into full contact along adjacent surfaces of adjacent sections, with the work-engaging surfaces of the sections becoming coplanar.

7. In a sheet-metal working hammer, a divided head portion comprising a body having a center recess and having a series of marginal recesses angularly spaced about and communicating with the center recess; a plurality of segmentally shaped impact sections having arms extending into said center recess, said arms being formed with spherical enlargements rockably engaged in the several marginal recesses, for rocking of the arms upon the body, the sections rocking with their arms toward each other responsive to movement of the sections forcibly against a work piece, said sections comprising a generally hemispherical impact head; and resilient, yielding means within the center recess normally biasing the sections away from each other, each of said sections being of quadrantal shape, said work-engaging faces of the several sections being roughened for gripping the work piece.

8. In a sheet-metal working hammer, a divided head portion comprising a body; a plurality of segmentally shaped impact sections arranged in said body about a common center, the several sections being mounted upon the body for pivotal movement toward and away from said center in paths radiating therefrom about fulcrum points individual to the several sections and angularly spaced about said center; and means interposed between the sections and body resiliently, yieldably biasing the sections about said points away from said center to normally space the sections therefrom.

9. In a sheet-metal working hammer, a divided head portion comprising a body; a plurality of like, segmentally shaped impact sections arranged in said body about a common center, the several sections being mounted upon the body for pivotal movement toward and away from said center in paths radiating therefrom about fulcrum points individual to the several sections, said fulcrum points being angularly spaced about said center in a common plane; and a spring centered in respect to and common to the several sections, said spring being interposed between the several sections and the body and being stressed to exert its pressure against the sections in a path normal to said plane, said spring exerting its pressure in a direction to bias the sections about said points away from said center, so as to normally space the sections therefrom.

10. In a sheet-metal working hammer, a divided head portion comprising a body; a plurality of like, segmentally shaped impact sections arranged in said body about a common center, the several sections being mounted upon the body for pivotal movement toward and away from said center in paths radiating therefrom, about fulcrum points individual to the several sections, said fulcrum points being angularly spaced about said center in a common plane, the impact sections projecting at one end out of the body and being formed with flat work-engaging surfaces at said one end, the other ends of the sections being formed with arms extending radially outwardly from ,said center, the fulcrum points being disposed at the outer ends of said arms; and resilient, yielding means interposed between the body and said other ends of the sections, said means being stressed to exert pressure against the sections in a direction efiective to bias the sections about said points away from said center, thus to normally space the sections from the center.

11. In a sheet-metal working hammer, a divided head portion as in claim 10 wherein the body has a center recess receiving said other ends of the sections, the body being formed with slots communicating with said center recess, the arms extending through said slots and being formed, at the outer ends of the arms, with spherically shaped enlargements, the body being formed with recesses complementing ,said enlargements and communicating with the slots-to provide the rockable mounting of the sections in the body.

12. In a sheet-metalworking hammer, a divided head portion ,as in claim 11 wherein said means comprises a compression coil spring seated in the center recess in engagement with said other ends of the several impact sections.

References Cited in the file of this patent UNITED STATES PATENTS 1,464,434 Ljungstrom Aug. 7, 1923 2,357,204 Joyner Aug. 29 1944 2,407,573 Nelson Sept. 10, 1946 2,699,079 Eck0ld et a1. Ian. 11, 1955 2,829,546 Moore Apr. 8, 1 958 

